OpenSource: How to build and install calendar/ligntning to thunderbird from source

1. prepare your .mozconfig, build it
(python client.py checkout && make -f client.mk)
mk_add_options MOZ_OBJDIR=@TOPSRCDIR@/objdir-tb-debug
ac_add_options --enable-application=mail
ac_add_options --enable-calendar
#ac_add_options --enable-debug

2. launch your thunderbird -> tools -> add-ons
3. find the  lightning.xpi you just built
e.g ./objdir-tb-debug/mozilla/dist/xpi-stage/lightning.xpi

4. drag lightning.xpi to the add-ons panel.

5. done!